This invention relates to a torch for powder plasma buildup welding, and more particularly to a powder plasma buildup welding torch wherein a torch head is inserted into a pipe material to be subjected to buildup welding, to thereby carry out the welding on an inner peripheral surface of the pipe material.
A typical torch for powder plasma buildup welding which has been conventionally known or practiced in the art includes a torch head and a torch body for connecting a body of a welding machine such as a power supply or the like and the torch head to each other therethrough and is adapted to carry out buildup welding on an inner peripheral surface of a pipe material. Such a welding equipment is constructed so as to rotate the pipe material while keeping the torch head and a part of the torch body inserted into the pipe material and move the torch head in the pipe material to form a spiral padding on the inner peripheral surface of the pipe material, to thereby attain buildup welding on the pipe material. Such a torch for powder plasma buildup welding is used to carry out buildup welding on an inner surface of a pipe material for a petroleum reaction pipe, an injection molding cylinder or the like using a welding material which has corrosion resistance and wear resistance.
Unfortunately, the conventional powder plasma buildup welding torch must be varied in construction depending on dimensions of a pipe material, a configuration thereof and the like, resulting in handling thereof being troublesome. In a powder plasma buildup welding torch, the torch body is formed of a rigid material, to thereby fail to construct the whole torch in a compact manner, so that transport of the torch is troublesome. This renders repairing of the torch head highly hard when any failure or trouble occurs in the torch head.
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a torch for powder plasma buildup welding which is capable of being readily handled irrespective of dimensions of a pipe material, a configuration thereof and the like.
It is another object of the present invention to provide a torch for powder plasma buildup welding which is capable of facilitating repairing of a torch head when it fails or breaks down.
It is a further object of the present invention to provide a torch for powder plasma buildup welding which is capable of restraining a variation in distance between an opening of a convergent nozzle of a torch head and an inner peripheral surface of a pipe material to be subjected to welding, to thereby form a padding uniform in size thereon.
It is still another object of the present invention to provide a torch for powder plasma buildup welding which is capable of preventing leaping of a torch body.
In accordance with the present invention, a torch for powder plasma buildup welding is provided. The torch includes a torch head adapted to be inserted into a pipe material of a continuous length to carry out buildup welding on an inner peripheral surface of the pipe materiall and a torch body formed into a continuous length and having the torch head mounted on a distal end thereof. The torch head is replaceably connected to the torch body. Such construction permits buildup welding to be attained in conformity to any size of a pipe material to be subjected to welding, any configuration thereof and the like. Thus, the present invention facilitates application of the torch to welding while eliminating replacement of the whole powder plasma buildup welding torch required in the prior art. Also, when any failure or trouble occurs in the torch head, the torch head may be readily repaired because it is detached from the torch body.
In general, the torch head includes a convergent nozzle having an opening. In a preferred embodiment of the present invention, either torch head or torch body is provided with a gap formation spacer member which is abutted against the inner peripheral surface of the pipe material to keep a distance between the opening of the convergent nozzle of the torch head and the inner peripheral surface of the pipe material substantially constant when welding takes place. Such arrangement of the gap formation spacer member in the torch effectively prevents a variation in distance between the opening of the convergent nozzle of the torch head and the inner peripheral surface of the pipe material subjected to welding due to a weight of the torch head and/or deflection of the torch body, to thereby ensure formation of a padding of a uniform size on the inner peripheral surface of the pipe material.
An increase in length of the torch body tends to cause it to be deflected in the pipe material during buildup welding. In particular, arrangement of the gap formation spacer member causes leaping of the torch body during rotation of the pipe material depending on abutment between the gap formation spacer member and the inner peripheral surface of the pipe material, leading to an increase in deflection of the torch body. In view of such a disadvantage, the torch body is preferably provided with at least one deflection restraint spacer member adapted to be abutted against the inner peripheral surface of the pipe material so as to prevent deflection of the torch body in the pipe material during buildup welding.
More specifically, in accordance with the present invention, a following torch for powder plasma buildup welding is provided. The torch includes a torch head adapted to be inserted into a pipe material of a continuous length to carry out buildup welding on an inner peripheral surface of the pipe material and a torch body formed into a continuous length and having the torch head mounted on a distal end thereof. The torch body includes a connection pipe and a plurality of pipes arranged in said connection pipe. The plurality of pipes feed cooling water, gas and the like to said torch head, respectively. The plurality of pipes include two or more pipes made of an electrically conductive material. One of the two or more pipes constitutes a first conductive portion electrically connected to one of electric poles of a DC power supply and another of the two or more pipes constitutes a second conductive portion electrically connected to the other of said electric poles. The torch head includes a bar-like electrode, an electrode support made of an electrically conductive material and arranged for supporting the bar-like electrode, a convergent nozzle made of an electrically conductive material, a nozzle support made of an electrically conductive material and arranged for supporting said convergent nozzle, and a head-side insulation member arranged between the electrode support and the nozzle support to electrically insulate the electrode support and nozzle support from each other. The head-side insulation member includes a projection portion projecting beyond the electrode support and nozzle support and toward the torch body. The connection pipe of the torch body is fixedly provided on an end thereof defined on a side of the torch head with an insulation flange. The insulation flange is attached with a connection member. The connection member includes a first connection member half and a second connection member half which are arranged so as to be spaced from each other through a cavity defined therebetween and fitted with the projection portion. One of the two or more pipes mentioned above is connected with the first connection member half through the insulating flange. Another of the two or more pipes mentioned above is connected with the second connection member half through the insulating flange. The electrode support is contacted with the first connection member half. The nozzle support is contacted with the second connection member half. The torch head is replaceably connected to the torch body by means of a plurality of bolts for fixing the torch head and connection member to each other.
The torch of the present invention thus constructed facilitates detachable connection between the connection member and the torch head by tightening and releasing of the bolts. This permits the torch head to be replaceably connected to the torch body by means of bolts. Also, connection between the connection member and the torch head leads to joining between the first connection member half and the electrode support, so that a current may be fed from one of electric poles of a power supply (a body of a welding machine) through one of the two or more pipes constituting a first conductive portion, the first connection member half and the electrode support to the bar-like electrode. Also, connection between the connection member and the torch head permits the second connection member half and nozzle support to be joined together, so that a current may be fed from the other electric pole of the power supply (the body of the welding machine) through another of the two or more pipes constituting a second conductive portion, the second connection member half and the nozzle support to the convergent nozzle.
In this invention, particularly, the head-side insulation member includes the projection portion. Thus the positioning between the torch head and the torch body is easily performed only by fitting the projection portion into the cavity defined between the first connection member half and the second connection member half. The connection member may be attached with the insulation flange by means of the bolts for fixing the torch head and the connection member to each other. This permits the torch head, the connection member and the insulation flange to be fixed together by means of a small number of bolts.
In a preferred embodiment of the present invention, the first connection member half and the second connection member half each are formed with a plurality of connection member-side bolt insertion through-holes. The flange is formed with a plurality of flange-side bolt insertion through-holes aligned with the connection member-side bolt insertion through-holes, respectively. The flange-side bolt insertion through-holes each include a large diameter portion receiving therein each head of the bolts and a small diameter portion receiving therein each shank of the bolts. The electrode support and the nozzle support each are formed with a plurality of threaded holes aligned with the connection member-side bolt insertion through-holes, respectively. The torch head is detachably connected to the torch body by means of bolts threadedly fitted in the threaded holes of the torch head through the connection member-side bolt insertion through-holes and flange-side bolt insertion through-holes. Such construction permits the connection member and torch head to be connected to each other by inserting bolts through the connection member-side bolt insertion through-holes and flange-side bolt insertion through-holes and threadedly fitting the bolts in the threaded holes of the torch head. Release of the bolts leads to separation of the connection member and torch head from each other.
In a preferred embodiment of the present invention, the insulation flange is formed with flange-side through-holes via which the pipes of the torch body extend and the connection member is formed with fit holes which communicate with the flange-side through-holes and in which the pipes are fitted and communication holes which communicate with the fit holes and are open on a side of the torch head. The torch head is formed with in-head passages aligned with the communication holes. The torch head is connected to the torch body so that the communication holes and in-head passages may communicate with each other at communication portions therebetween. Thus, connection between the connection member and the torch head leads to communication between the communication holes and the in-head passages, so that a current, cooling water, gas and the like may be fed from the body of the welding machine to the torch head.
In a preferred embodiment of the present invention, the communication portions, at which the communication holes and in-head passages communicate with each other, each are sealed at a peripheral edge thereof with an O-ring which is arranged at an opening of each of the communication holes on a side of the torch head or an opening of each of the in-head passages on a side of the connection member. This permits the peripheral edge of the communication portion between the communication holes and the in-head passages to be effectively sealed with the O-ring compressed due to tightening of the bolts.
In a preferred embodiment of the present invention, the torch body is provided on an end thereof defined on a side of the torch head with an above-mentioned gap formation spacer member and the torch body is provided with an above-mentioned deflection restraint spacer member.
The gap formation spacer member may be constructed in any desired manner. For example, the gap formation spacer member may include an upper head support half and a lower head support half which are combined with each other to circumferentially surround the torch body. In this instance, the lower head support half may include a lower body portion for circumferentially surrounding a lower portion of the torch body and a lower projection portion arranged so as to vertically downwardly project from the lower body portion, resulting in being abutted against the inner peripheral surface of the pipe material. The upper head support half may include an upper body portion for circumferentially surrounding an upper portion of the torch body and an upper projection portion arranged so as to project from the upper body portion in a radial direction of the pipe body, resulting in being abutted against the inner peripheral surface of the pipe material. The upper projection portion may have, to the lower projection portion, positional relationship which is set to restrain a variation in distance between the torch head and the inner peripheral surface of the pipe material during welding.
In a preferred embodiment of the present invention, the lower projection portion includes a projection body threadedly coupled to the lower head support half and a ball member supported in the projection body in a rollable manner (hereinafter also referred to as xe2x80x9crollablyxe2x80x9d) so as to be abutted against the inner peripheral surface of the pipe material. This permits rotation or rolling of the ball member to reduce friction between the lower projection portion and the inner peripheral surface of the pipe material, to thereby reduce deflection of the torch body in the pipe material during buildup welding.
In a preferred embodiment of the present invention, the insulation flange is formed into a cylindrical configuration and constitutes the gap formation spacer member. In this instance, the insulation flange may be abutted against the inner peripheral surface of the pipe material. This eliminates a necessity of providing the gap formation spacer member separately and simplifies a structure of the gap formation spacer member.
The deflection restraint spacer member may be likewise constructed in any desired manner. For example, the deflection restraint spacer member may include an upper body support half and a lower body support half which are combined with each other to circumferentially surround the torch body, as well as an abutment member arranged so as to vertically downwardly project from the lower body half, resulting in being abutted against the inner peripheral surface of the pipe material. The abutment member may be formed into a plate-like shape and arranged so as to extend in a longitudinal direction of the pipe material to be welded. Also, the deflection restraint spacer member may be constituted by a cylindrical member. The cylindrical member may include a first body support half and a second body support half which are combined with each other to circumferentially surround the torch body.